This invention relates to internal combustion engines, and more particularly to balancing systems for such engines.
Balancing systems for internal combustion engines are used to balance the reciprocating forces due to piston movement and the rotational forces due to crankshaft and crank pin rotation. Many systems are known for counterbalancing these reciprocal and rotational forces. Typical balancing systems use one or more additional balancing shafts, with each additional shaft having a gear that meshingly engages a gear on another shaft, on the crankshaft, or on a shaft attached to the crankcase. Counterbalance weights rotate with the rotation of the additional shaft to balance the reciprocating and rotational forces.
The use of additional shafts, gears and counterweights in such prior art devices increases the cost of the balancing system by fifty per cent or more, and therefore increases the cost of the entire engine.
Many prior art balancing systems use one or more counterbalance weights which rotate at a speed other than the speed of the crankshaft. For example, such counterbalance weights may rotate at camshaft speed, which is typically one-half that of the crankshaft rotation speed. Since the balancing system is designed to balance the crankshaft rotational forces, a counterbalance weight that rotates at any speed other than crankshaft speed typically does not optimally balance the crankshaft rotational forces.